Developer options let you access parts of Android you would otherwise be unaware of. In the latest version of Android they are hidden very well: you have to go to Settings>About phone and tap the Build number section 7 times for them to appear. It will be worth the effort, however.

USB debugging

This feature lets you connect an Android device to a desktop computer to transfer data between each device and to install apps directly without any standard notifications.

Stay awake

Stay awake performs an obvious task and that is to keep the screen awake when charging. This is useful if you need an onscreen clock or photo slideshow running.

Allow mock locations

This clever feature allows you to fake your location and to not be stuck with your current GPS co-ordinates. You can then search for other areas quickly when planning trips.

Show CPU usage

Even though this feature is designed for developers, you can also use it to show the current CPU usage at any time which is useful for finding apps that are using all of your processing power.

Background process limit

If you own a device that is lacking in processing power and memory, you can use this feature to limit the number of background process that can run between 0 and 4 processes.

Do not keep activities

This will close apps etc as soon as you switch away from them. Turning this on will likely adversely affect your device’s performance.

Show touches

A simple option that will visually highlight each point on the screen as you touch it. It is designed for development, but is actually useful for day to day tasks.

Force GPU rendering

This makes use of hardware acceleration in apps where it is not explicitly supported. It can improve performance and reduce, but it may also cause issues with non-compatible apps.

Window animation/Transition animation/Animator duration scale

These options determine how long animations last as you swipe between screens and windows and boxes open. Adjusting them can make the system feel smoother or snappier.